With increasing demand for liquid transportation fuels, decreasing reserves of ‘easy oil’ (crude petroleum oil that can be accessed and recovered easily) and increasing constraints on carbon footprints of such fuels, it is becoming increasingly important to develop routes to produce liquid transportation fuels from biomass in an efficient manner. Such liquid transportation fuels produced from biomass are sometimes also referred to as biofuels. Biomass offers a source of renewable carbon. Therefore, when using such biofuels, it may be possible to achieve more sustainable CO2 emissions over petroleum-derived fuels.
An efficient, self-contained method for processing biomass into high quality liquid fuels is described in WO 2010/117437 A1, in the name of Gas Technology Institute. Said method may include one or more of the steps of a) hydropyrolysing biomass in a hydropyrolysis reactor vessel containing molecular hydrogen and a deoxygenating catalyst, producing a mixture of light gases containing predominantly CO2, H2O, CO and C1-C3 gas, vapours containing partially deoxygenated products of hydropyrolysis, char, ash and fines of deoxygenating catalyst; b) removing said char, ash and deoxygenating catalyst fines from said light gases and vapours containing partially deoxygenated products of hydropyrolysis; c) processing the vapours containing partially deoxygenated products of hydropyrolysis in a hydroconversion reactor vessel using a hydroconversion catalyst in the presence of the H2O, CO2, CO and C1-C3 gas generated in step a), producing a substantially fully deoxygenated hydrocarbon liquid and a gaseous mixture comprising CO, H2O, CO2, and light hydrocarbon gases (C1-C3); d) steam reforming a portion of said C1-C3 gaseous mixture, and water-gas shifting the CO, producing molecular hydrogen; and e) introducing said molecular hydrogen into said reactor vessel for hydropyrolysing said biomass, wherein steps a) and c) are operated at conditions under which about 30-70% of oxygen in said biomass is converted to H2O and about 30-70% of said oxygen is converted to CO and CO2. The reformed hydrogen may then be used in said process as the hydrogen source in step a).
A process for producing liquid hydrocarbons from biomass that utilizes a downstream hydroprocessing reactor and reduced metal catalysts is described in co-pending application PCT/EP2015/051709.
The product from these processes may be further separated to produce diesel fuel, gasoline or blending components for gasoline and diesel fuel.
Different specifications for gasoline and diesel fuel may be required in different locations. Material not meeting these specifications may be used as a blending component in a fuel or may need to be upgraded in order to be used as a blending component or as the fuel itself.
Hydrocarbon liquid products produced from biomass by hydropyrolysis-based processes may not fulfill the specifications required for diesel and gasoline range products in a number of locations. For example, such material may have undesirable distribution of various classes or hydrocarbon molecules (aromatics, paraffins and naphthenes) resulting in, for example, poor octane number of gasoline and poor cetane number of diesel product.
The art of hydropyrolysis, therefore, would benefit significantly from processing options that allow flexibility in terms of providing hydrocarbon-containing product fractions in varying yields and compositions, and with desired product quality attributes (e.g. cold flow properties in the case of a diesel boiling range fraction or octane number in the case of a gasoline boiling range fraction). Such processing options could be adapted as needed to meet changing end-product demands in the art of renewable fuels, thereby maximizing overall value and process economics.